Keep in mind the main reason to assume a mortgage; it is to get yourself into a mortgage that you may not qualify for otherwise. You don't get a "deal" in general when assuming.
One thing I found when I bought my house (assumed mortgage); is that my first realtor told me that an assumable was near to impossible, and to hold onto my deposit until I would qualify on my own. (Had I done that I would have lost the $150K I've made in equity in my current house.) I found the realtor who sold me my house by an ad in the Sun; he advertized that he specialized in assumables.
I do think an assumable will be harder to find now. You will have to find somebody who bought 2 months ago and now suddenly cannot afford the mortgage. My house that I've been in for 2 years now; you'd need $200K to assume my mortgage.
Then add the info that Troutman gave, and it might be a tough proposition.